The plug used for a miniature light bulb series typically includes a plug body with two extended conductor wires. These conductor wires extend from the interior of the plug body and are connected to sockets and light bulbs to form a decorative light bulb series. As disclosed in U.S. Pat. Nos. 4,684,914; 5,154,642; and 5,320,563, such conventional structures make it necessary that the terminals of conductor wires must be put into the interior of the plug to get in touch with conductor copper blades while the plug is assembled. However, in a practical production operation, the electrical wire supplier and the plug maker often are not the same. Even if some companies produce both, plugs and wires are scarcely made at the same site. As a consequence, the plug makers have to acquire conductor wires before the production starts and only plugs integrated with conductor wires can be delivered to downstream assemblers for further processing. This is inconvenient for the production of plugs. Moreover, the procedure of incorporating conductor wires with terminals into a plug is rather complex. It is desirable to have an improvement on the conventional plug structure.
In view of the above-mentioned problems, the primary object of the invention is to provide an improved plug structure in which the deficiency of a conventional plug is eliminated and that can be made as an independent part used for further assembling, without the necessity of combination with conductor wires in advance. Now the detailed structure and features of the invention will be described here with reference to accompanying drawings.